Triterpenoids from Dysoxylum malabaricum

New ring-A modified cycloartane triterpenoids from Dysoxylum malabaricum bark: Isolation, structure elucidation and their cytotoxicity

The Genus Dysoxylum (Meliaceae) consists of approximately 80 species that are abundant in structurally diverse triterpenoids. The present study focused on isolating new triterpenoids from the bark of Dysoxylum malabaricum, one of the predominant species of Dysoxylum present in India. The methanol-dichloromethane bark extract was subjected to LCMS profiling followed by silica gel column chromatography and HPLC analysis to target new compounds. Two new ring A-modified cycloartane-type triterpenoids (1 and 2) were isolated from the bark extract. Spectroscopic methods like NMR, HRESIMS data, and electronic circular dichroism calculations elucidated the structuresandabsolute configurations of the isolated compounds. These compounds were evaluated for their cytotoxic potential against breast cancer cells and displayed notable cytotoxicity. Compound 1 exhibited the highest cytotoxicity against the MDA-MB-231 cells and induced apoptotic cell death. Also, it was able to inhibit glucose uptake and increase nitric oxide production in breast cancer cells.

New cycloartane triterpenoids from Dysoxylum malabaricum and their cytotoxic evaluation

The cytotoxic dichloromethane-methanol bark extract of Dysoxylum malabaricum was subjected to bioassay-guided fractionation, followed by systematic dereplication to focus on the identification of new compounds. From the bark of Dysoxylum malabaricum, two new cycloartane-type triterpenoids were isolated in addition to two previously known triterpenoids. The structures and absolute configurations of the isolated compounds were elucidated unambiguously via NMR, HRESIMS data, and electronic circular dichroism calculations. The isolated compounds were tested for their cytotoxic potential against the panel of breast, lung, and hypopharynx cancer cell lines and displayed notable cytotoxicity against breast cancer cell lines. Compound 3 exhibited the most potent cytotoxic effect with an IC50 14 µM against MCF-7 cell lines and induced cell cycle arrest. Through western blot and cell cycle analysis, it was revealed that compound 3 halts the G0/G1 phase of the cell cycle by inhibiting CDC20 and CDC25 enzymes.

Triterpenoids from Dysoxylum genus and their biological activities

This study aims to analyze the ethnobotanical, chemical, and biological activities of triterpenoid compounds isolated from the Dysoxylum genus of the Meliaceae family between 1974 and 2021. The species are mainly distributed in Africa, Asia, and Australia, and used as a traditional medicine to treat various diseases. Triterpenoid was first isolated in 1976 and as tetranortriterpenoid or limonoid, it was named dysobinin. Several studies were conducted for more than 40 years on the plants' stems, bark, and leaves, where approximately 279 triterpenoid compounds from several groups such as dammarane, nortriterpenoid, oleanane, lupane, tirucallane, cyclolanostane, or cycloartane, glabretal, and cycloapoeuphane-types were isolated with some synthetic products. In addition, the hypothetical route of triterpenes biosynthesis from this genus was identified, and tirucallane-type were reported to be 37.6% of the total compounds. The anti-malarial, anti-feedant, antimicrobial, anti-inflammatory, antioxidant, vasodilative effect, anti-viral, cortisone reductase, and cytotoxic activities of the extract were also evaluated. The results showed the necessity of using the triterpenoid compounds from the Dysoxylum genus in traditional medicine and the discovery of new drugs.

Euphorfistrines A-G, cytotoxic and AChE inhibiting triterpenoids from the roots of Euphorbia fischeriana

Seven new triterpenoids including two cycloartanes (1-2), a lanostane (3), a tirucallane (4), a dammarane (5), an ursane (6), and an oleanane (7), along with nineteen known triterpenoids (8-26), have been obtained from the roots of Euphorbia fischeriana. Their structures were established by NMR, HRESIMS, single-crystal X-ray diffraction analysis, Mosher's method, NMR calculations, ECD analysis, and comparison with structurally related known analogues. Among them, compounds 1 and 8 were a pair of cycloartane-type triterpenoids epimers. Our bioassays have established that compounds 1-5 and 10 displayed moderate cytotoxic effects, and the structure-activity relationships of cycloartane-type triterpenoids (CTTs) were further examined. Notably, some triterpenoids displayed moderate inhibitory effects against AChE by an in vitro screened experiment. Triterpenoid 7 (Euphorfistrine G, ETG) displayed the potent inhibitory effect with IC₅₀ = 2.45 and K_i = 2.30 μM (inhibition kinetic). And, in silico docking analyses have been performed to investigate the inhibitory mechanism of compound 7.

Hirtinone, a Novel cycloartane-type triterpene and other compounds from Trichilia hirta L. (Meliaceae)

One novel triterpene cycloartane-type, named hirtinone (1), six protolimonoids – nilocitin (2), dihydronilocitin B (3), melianone epimers (4) and (5), piscidinol A (6) and melianone lactone (7), one tertranortriterpenoid, hirtin (8), and one sesquiterpene, spathulenol (9), were identified in the fruits of Trichilia hirta. The structures were established by 1D and 2D NMR (¹H and ¹³C-NMR, DEPTQ, ¹H-¹H-COSY, ¹H-¹H-NOESY, HSQC and HMBC), high resolution mass spectroscopy (HR-ESI-MS) and infrared (IR) spectral data.

Triterpenes from Euphorbia rigida

Phytochemical studies of the aerial parts of Euphorbia rigida afforded three triterpenes: betulin (1), cycloart-23Z-ene-3, 25-diol (2) and cycloartan-3, 24, 25-triol (3), firstly isolated from this plant. The structures and relative stereochemistry were determined on the basis of extensive spectroscopic analyses, including 1D and 2D NMR experiments (1H NMR, 13C NMR, COSY, NOESY, HMQC and HMBC).

Toxicity and behavioral effect of 3beta,24,25-trihydroxycycloartane and beddomei lactone on the rice leaffolder Cnaphalocrocis medinalis (Guenée) (Lepidoptera: Pyralidae)

Treatment of Dysoxylum pure triterpenes 3beta,24,25-trihydroxycycloartane and beddomei lactone to the rice leaffolder (RLF), Cnaphalocrocis medinalis (Guenée) (Lepidoptera: Pyralidae), resulted in prolonged larval duration and reduced larval weight. In leaf cut choice assay and topical application experiments, beddomei lactone and 3beta,24,25-trihydroxycycloartaneto showed strong antifeedant and growth inhibitor activity against fourth instar larvae of C. medinalis. Also average leaf consumption was decreased (89%) by the treatment of the two terpinoids when compared with controls. Number of eggs laid by the female (fecundity) was decreased and oviposition deterrence index was increased due to the treatment. This result further shows that the pure triterpenes of Dysoxylum act as both an antifeedant and chronic toxin to the rice leaffolder larvae.

Terpenoids from Toona ciliata

Three new norlimonoids (1-3), two new tirucallane-type triterpenoids (4 and 5), and a new pimaradiene-type diterpenoid (6), along with two known limonoids and eight known tirucallane-type triterpenoids, were isolated from the leaves and twigs of Toona ciliata. Their structures were elucidated on the basis of spectroscopic data. Toonaciliatin M (6) showed moderate antifungal activity against Trichophyton rubrum with an MIC of 12.5 microg/mL.

Larvicidal and growth inhibition of the malaria vector Anopheles stephensi by triterpenes from Dysoxylum malabaricum and Dysoxylum beddomei

Secondary metabolites from Dysoxylum malabaricum and Dysoxylum beddomei were tested against mature and immature stage of the mosquito vector Anopheles stephensi under laboratory conditions. The triterpenes 3beta,24,25-trihydroxycycloartane and beddomeilactone from D. malabaricum and D. beddomei showed strong larvicidal, pupicidal and adulticidal activity. They also affected the reproductive potential of adults by acting as oviposition deterrents. The highest concentration tested (10 ppm) of both compounds evoked more than 90% mortality and oviposition deterrence.

Effects of Dysoxylum malabaricum Bedd. (Meliaceae) extract on the malarial vector Anopheles stephensi Liston (Diptera: Culicidae)

In recent years, use of environmentally friendly and biodegradable natural insecticides of plant origin have received renewed attention as agents for disease vector control. Methanol extracts of leaves from the Indian white cedar Dysoxylum malabaricum Bedd. (Meliaceae) were tested against mature and immature Anopheles stephensi Liston (Diptera) mosquitoes under laboratory conditions. The extract showed strong larvicidal, pupicidal, adulticidal, and antiovipositional activity. The maximum leaf extract concentration tested in this study was 4%, which produced pronounced effects. In general, first and second instars were more susceptible to leaf extract than older insects. Clear dose-response relationships were established, with the highest dose of 4% plant extract causing 97% mortality of first instars.

Beddomeilactone: A New Triterpene fromDysoxylum Beddomei

An investigation of the leaves of Dysoxylum beddomei has yielded a novel triterpene, named beddomeilactone, together with six known triterpenoids: 3-oxotirucalla-7,24-dien-23-ol, dipterocarpol, niloticin, melianone, melianodiol and 24-epi-melianodiol. The structure and stereochemistry of the new compound were determined on the basis of mass, 1D and 2D NMR spectroscopies including NOE difference and spin-spin decoupling studies.